JP2009218159A - Cylindrical alkaline battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical alkaline battery capable of surely preventing short circuiting between positive and negative electrodes originating from reaction of impurities containing copper with a positive electrode mixture. <P>SOLUTION: For the cylindrical alkaline battery 10a provided with a positive electrode can 11 of a bottomed cylinder shape with a top part open, a positive electrode mixture 12 molded into a hollow cylinder shape containing manganese oxide and insertion-fitted into the positive electrode can, a gel-like negative electrode 14 containing zinc and filled in the hollow cylinder of the positive electrode mixture through a separator 13, an negative electrode terminal plate 16 fitted into the opening part of the positive electrode can through gasket 17, an negative electrode collector 15 spot-welded on an underside of the negative electrode terminal plate with a meta rod containing copper to be inserted into the gel-like negative electrode, the top face of the positive electrode mixture of the hollow cylinder shape is covered with a cover 20 of the same end-face shape. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cylindrical alkaline battery, and more specifically to a cylindrical alkaline battery that can prevent an internal short circuit due to impurities including copper.

  FIG. 2 shows the structure of an LR6 type alkaline battery as a conventional cylindrical alkaline battery. The battery 10b includes a bottomed cylindrical metal battery can (positive electrode can) 11, a positive electrode mixture 12 formed into a hollow cylinder containing manganese dioxide as a positive electrode active material, and disposed inside the positive electrode mixture 12. Separator 13 provided, gelled negative electrode (negative electrode gel) 14 containing zinc filled inside separator 13, negative electrode current collector 15 inserted into negative electrode gel 14, negative electrode terminal plate 16, sealing gasket 17, etc. Consists of.

  In this structure, the positive electrode can 11 has a positive electrode terminal 18 formed at the bottom and functions as a positive electrode current collector by directly contacting the positive electrode mixture 12 on the inner surface of the cylinder. A rod-shaped metal negative electrode current collector 15 inserted in the negative electrode gel 14 is erected and fixed on the inner surface of a dish-shaped metal negative electrode terminal plate 16 by spot welding. In the illustrated structure, the negative electrode terminal plate 16 also serves as a sealing plate that serves as a “lid” for the positive electrode can 11, and the negative electrode terminal plate 16, the negative electrode current collector 15, and the sealing gasket 17 are combined together in advance. The outer periphery of the sealing gasket 17 is clamped between the opening edge of the positive electrode can 11 and the peripheral edge of the negative electrode terminal plate 16, and the positive electrode can 11 is hermetically sealed.

  By the way, the negative electrode current collector 15 is generally made of brass which is an alloy of copper and zinc. When the negative electrode current collector 15 is spot-welded to the inner surface of the negative electrode terminal plate 16, brass powder may scatter and adhere to the sealing gasket 17 or the like. Therefore, if the positive electrode can 11 is sealed with the sealing gasket 17, there is a possibility that the adhering brass powder is peeled off and mixed into the positive electrode can 11 during the sealing process and the period when the manufactured battery is stored. is there. When copper contained in the brass powder comes into contact with manganese dioxide constituting the positive electrode mixture 12 in the electrolyte, it is oxidized to copper ions. When the copper ions move to the negative electrode side through the separator 13, zinc in the negative electrode gel 14 is dissolved and copper metal is deposited on the separator 13. The deposited copper penetrates the separator 13 and causes a short circuit between the positive electrode and the negative electrode.

In addition, although not copper, the following patent document 1 similarly describes a technique for preventing a short circuit due to zinc metal derived from impurities including copper in contact with the positive electrode active material. In this technique, a part where the metal is likely to precipitate in the separator, for example, a part in contact with the end face on the negative electrode terminal plate (positive electrode can opening) side of the positive electrode mixture close to the impurity mixing path is heat-sealed, or polyvinyl chloride is attached to the part. After applying a solution such as alcohol (PVA), the solution is heated and dried to solidify a part of the separator. Or the cellophane film is stuck on the said location. Thereby, the deposited zinc metal is prevented from penetrating the separator.
Japanese Unexamined Patent Publication No. 7-85855

  The technique described in Patent Document 1 seems to be able to prevent a short circuit due to copper deposition. However, when the separator is solidified by heat fusion or heat drying of the solution, the separator has a discontinuous mechanical strength at the boundary between the solidified portion and the normal soft portion, and may be broken at this boundary portion. . In addition, since the cellophane film cannot completely block ions, copper ions generated on the positive electrode side may move to the negative electrode side, and it is difficult to completely prevent copper deposition. Therefore, in the above prior art, it has not been possible to reliably prevent the positive and negative electrodes from being short-circuited due to the reaction between the impurity containing copper and the positive electrode active material.

  Accordingly, an object of the present invention is to provide a cylindrical alkaline battery that can reliably prevent a short circuit between positive and negative electrodes originating from the reaction of impurities containing copper with the positive electrode mixture.

  The present invention was made on the basis of the idea of preventing the occurrence of copper ions, which are fundamental causes of copper precipitation, rather than preventing the deposited copper from penetrating the separator. Is a bottomed cylindrical positive electrode can opened at the top, a positive electrode mixture formed into a hollow cylindrical shape containing manganese dioxide and inserted into the positive electrode can, and a positive electrode mixture containing zinc. A gel-like negative electrode filled via a separator in a hollow cylinder, a negative electrode terminal plate fitted via a gasket to the opening of the positive electrode can, and a rod-shaped metal containing copper on the lower surface of the negative electrode terminal plate A cylindrical alkaline battery including a negative electrode current collector that is spot-welded and inserted into the gelled negative electrode, and a cylinder in which an upper end surface of the hollow cylindrical positive electrode mixture is covered with a cover having the end surface shape Type alkaline battery There.

  The cover may be loosely fitted in an annular region between the inner surface of the positive electrode can and the outer surface of the separator. Furthermore, it is also possible to provide a cylindrical alkaline battery in which the upper end of the separator is in contact with the lower surface of the gasket so that the cover cannot deviate from the annular region. In the cylindrical alkaline battery, it is more preferable that the cover is made of an alkali-resistant resin.

  According to the cylindrical alkaline battery of the present invention, since the upper end surface of the hollow cylindrical positive electrode mixture is covered with the cover, copper is not oxidized into the positive electrode active material and becomes copper ions. Therefore, it is possible to reliably prevent a short circuit between the positive and negative electrodes resulting from the reaction of impurities containing copper with the positive electrode mixture, and it is possible to provide a cylindrical alkaline battery having high safety and reliability. In addition, it is possible to reduce the incidence of defects due to internal short circuits and to reduce the cost of cylindrical alkaline batteries.

=== Structure of cylindrical alkaline battery ===
FIG. 1 shows the structure of a cylindrical alkaline battery in an embodiment of the present invention. (A) is the longitudinal cross-sectional view of the said cylindrical alkaline battery, (B) is a cross-sectional view from the aa arrow direction in (A). The cylindrical alkaline battery 10a in this embodiment has substantially the same structure as the conventional cylindrical alkaline battery 10b shown in FIG. 2, but when the opening direction of the positive electrode can 11 is set upward, a hollow cylindrical positive electrode mixture 12 is used. The upper end surface is covered with a cover 20 having the same annular shape as the upper end surface.

  Since the positive electrode mixture 12 expands during the discharge reaction in the battery 10a, in this embodiment, the cover 20 has an annular ring between the inner surface of the positive electrode can 11 and the outer surface of the separator 13 so that the expansion is not suppressed. It is loosely fitted in the region and is allowed to move in the vertical direction. That is, it is placed on the upper end surface of the positive electrode mixture 12. The separator 13 has an upper end in contact with the gasket 17, and the cylindrical region filled with the negative electrode gel 14 and the annular region into which the positive electrode mixture 12 is inserted are surely partitioned by the separator 13. ing. As a result, the cover 20 does not deviate from the annular region by being inclined or the like, and the state in which the upper end surface of the positive electrode mixture 13 is reliably covered can be maintained.

  In the cylindrical alkaline battery 10a of the present embodiment, even if impurities including copper are mixed in the positive electrode can 11 in the manufacturing process of the battery 10a or the storage period after manufacturing, the impurities are present because the cover 20 is present. Does not come into contact with the positive electrode mixture 13. Therefore, copper ions that cause copper deposition do not occur, and a short circuit between the positive and negative electrodes (internal short circuit) can be reliably prevented.

=== Performance evaluation ===
In order to evaluate the performance of the cylindrical alkaline battery according to the present invention, the cylindrical alkaline battery (invention) 10a according to the present invention shown in FIG. 1 and the conventional cylindrical alkaline battery (conventional product) shown in FIG. Product) 10b was prepared as a sample. The sample was an LR6 type alkaline battery, and for the inventive product, a plurality of types of samples were produced by changing the material of the cover 20 in various ways. One million samples were produced for each sample, and after leaving these samples to stand for one month, the performance was evaluated by the ratio of samples that caused an internal short circuit due to copper deposition (internal short circuit occurrence rate).

Table 1 shows the evaluation results.

  From Table 1, in the products (samples 1 to 4), no internal short circuit occurred in all cases, regardless of the material of the cover 20. On the other hand, in the conventional product (Sample 5), an internal short circuit occurred at a rate of 10 ppm. From the above, it was proved that the cylindrical alkaline battery according to the present invention can reliably prevent internal short circuit. In consideration of the possibility that the cylindrical alkaline battery will be stored for a longer period of time, the cover is resistant to alkalis that are not attacked by the electrolyte, and does not cause a redox reaction with the active material in the positive electrode mixture or the gelled negative electrode. It is desirable to form with resin (polyethylene, polybutene, polypropylene, etc.).

It is sectional drawing of the cylindrical alkaline battery in the Example of this invention. It is sectional drawing of the conventional cylindrical alkaline battery.

Explanation of symbols

10a, 10b Cylindrical alkaline battery 11 Positive electrode can 12 Positive electrode mixture 13 Separator 14 Negative electrode gel 15 Negative electrode current collector 16 Negative electrode terminal plate 17 Gasket 20 Cover

Claims (4)

  A bottomed cylindrical positive electrode can opened at the top, a positive electrode mixture formed into a hollow cylinder containing manganese dioxide and inserted into the positive electrode can, and a hollow cylinder of the positive electrode mixture containing zinc Spot-welded to the lower surface of the negative electrode terminal plate with a gelled negative electrode filled via a separator, a negative electrode terminal plate fitted via a gasket to the opening of the positive electrode can, and a rod-shaped metal containing copper In the cylindrical alkaline battery provided with the negative electrode current collector inserted into the gelled negative electrode, the upper end surface of the hollow cylindrical positive electrode mixture is covered with a cover having the end surface shape. A cylindrical alkaline battery.   The cylindrical alkaline battery according to claim 1, wherein the cover is loosely fitted in an annular region between the inner surface of the positive electrode can and the outer surface of the separator.   The cylindrical alkaline battery according to claim 2, wherein the upper end of the separator is in contact with the lower surface of the gasket so that the cover cannot deviate from the annular region.   The cylindrical alkaline battery according to claim 1, wherein the cover is made of an alkali resistant resin.

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